SHIATSU & SCIATICA - Shiatsu Society

Dep

artm

ent o

f Agr

icul

ture

and

Fis

heri

es

Bios

ecur

ity

Que

ensl

and

Anna Markula Steve Csurhes and Martin Hannan-Jones

First published 2010

Updated 2016

I n v a s i v e a n i m a l r i s k a s s e s s m e n t

Cane toadBufo marinus

2

I n v a s i v e a n i m a l r i s k a s s e s s m e n t Cane toad Bufo marinus

copy State of Queensland 2016

The Queensland Government supports and encourages the dissemination and exchange of its information The copyright in this publication is licensed under a Creative Commons Attribution 30 Australia (CC BY) licence

You must keep intact the copyright notice and attribute the State of Queensland as the source of the publication

Note Some content in this publication may have different licence terms as indicated

For more information on this licence visit httpcreativecommonsorglicensesby30audeeden httpcreativecommonsorglicensesby30audeeden

3

I n v a s i v e a n i m a l r i s k a s s e s s m e n t Cane toad Bufo marinus

ContentsSummary 4

Introduction 5

Identity and taxonomy 5

Description 6

Biology and ecology 6

Diet 7

Predators and diseases 8

Origin and distribution 9

Status in Australia and Queensland 10

Preferred habitat 11

History as a pest elsewhere 12

Current impact in Australia 12

Pest potential in Queensland 14

Climate match 14

Threat to human health 16

Legal status in Australia and Queensland 16

Numerical risk analysis 16

References 17

Attachment 22

4

I n v a s i v e a n i m a l r i s k a s s e s s m e n t Cane toad Bufo marinus

SummaryIIn 1935 about 100 cane toads (Bufo marinus) were introduced into Queensland from tropical America in a clumsy attempt to control cane beetles a significant pest of sugarcane crops Over the past 75 years cane toads have invaded most of coastal and sub-coastal Queensland and are currently spreading into new areas of the Top End in the Northern Territory and into north-west parts of Western Australia

Adult toads are generally 10ndash15 cm long and can eat a wide range of invertebrate and small vertebrate prey items Females can lay 8000ndash35 000 eggs once or even twice each year Cane toads have few predators due to their toxic paratoid glands and under favourable conditions can become very abundant While preferring open disturbed habitats (especially gardens and lawns in urban areas) cane toads can also prosper in more natural habitats such as tropical woodland and savannah They tend to be rare or absent in dense vegetation

While recognised as a somewhat iconic symbol of Queensland cane toads have caused significant environmental harm They are almost certainly causing the demise of certain species of unique native wildlife especially the northern quoll Their impact on a range of other animals (such as snakes goannas frogs and invertebrates) is somewhat unclear (especially at a long-term population level) but is generally perceived as significant

Climate-based modelling of the long-term potential distribution of cane toads in Australia suggests further spread across tropical and subtropical coastal and sub-coastal northern Australia For the most part semi-arid tropical and subtropical areas are probably marginal habitat but cane toads might persist in low numbers in any moist areas (such as along river banks and billabongs) within this zone

5

I n v a s i v e a n i m a l r i s k a s s e s s m e n t Cane toad Bufo marinus

Introduction Identity and taxonomySpecies identity Bufo marinus (Linnaeus 1758)

Synonyms Rhinella marinus

Chaunus marinus

A review of amphibian taxonomy placed Bufo marinus in the Chaunus genus Hence some authors refer to its new name Chaunus marinus (Frost et al 2006) More recent molecular studies placed B marinus in the Rhinella genus as Rhinella marinus (Chaparro et al 2007)

Common names cane toad giant neotropical toad marine toad bufo toad bullfrog giant American toad giant toad Suriname toad South American cane toad giant marine toad Dominican toad

Family Bufonidae

Similar species Some native burrowing frogs especially the Giant burrowing frog (Heleioporus australiacus) are sometimes mistaken for B marinus Giant burrowing frogs can be distinguished by their more vertical pupils (Figure 1) Perhaps the most distinctive feature of B marinus is a prominent sharp-edged ridge above each eye and the lack of bright colouring on the thighs (Wikipedia 2009a)

Bufo comprises about 150 species of true toads found throughout most of the world except for the Arctic Antarctic Australia New Guinea and neighbouring islands A unique feature of Bufo is a large parotoid gland behind each eye (Wikipedia 2009b)

Figure 1 Native giant burrowing frog (Heleioporus australiacus) (Photo LiquidGoul Wikimedia Commonsmdashimage reproduced under the terms of GNU Free Documentation)

6

I n v a s i v e a n i m a l r i s k a s s e s s m e n t Cane toad Bufo marinus

DescriptionBufo marinus is a heavily built amphibian Adults are generally 10ndash15 cm long with dry warty skin that can be grey yellowish olive-brown or reddish-brown The ventral surface is pale with dark mottling B marinus is sexually dimorphic with females growing significantly larger than males and having smoother skin Males develop nuptial pads (dark lumps) on their first two fingers during the mating season A median vocal sac also opens on each side of the mouth Well-developed cranial crests form ridges above the eyes and join above the snout The eyes are prominent and have horizontal pupils and golden irises Adults have parotoid glands (large triangular swellings) on each shoulder behind the eardrum Hind feet are webbed whereas front feet are not B marinus adopts a more upright stance when sitting on flat ground compared to native frogs Juvenile B marinus have smooth dark skin with darker blotches and bars and they lack parotoid glands Tadpoles are uniformly black and 22ndash27 mm long (Australian Museum 2003 CaneToadsinOzcom 2009 Easteal 1993 Wikipedia 2009a)

Biology and ecologyTadpole development Tadpoles emerge 48ndash72 hours after eggs are laid tadpoles can

develop into young toads (metamorphs) in 10 days ndash 6 months depending on local conditions

Number of eggs 8000ndash35 000 per clutch

Oviposition frequency Once or twice per year

Sexual maturity Reached when young toads are 65ndash90 mm in length and are usually in their second wet season in northern Australia

Life span At least five years in wild and up to 15 years in captivity

(Australian Museum 2003 Hero amp Stoneham 2009)

Breeding occurs throughout the year but tends to peak during periods of rain and warm weather In Australia breeding usually starts around September as temperatures begin to rise Water temperatures of 25ndash30 degC are required for healthy tadpole development (Australian Museum 2003)

The malersquos mating call is a high-pitched lsquobrrrsquo resembling the dial tone of a telephone (Gautherot 2000) Breeding sites are generally still or slow-flowing clear water with salinity levels up to 15 and an alkaline pH (Australian Museum 2003 Hero amp Stoneham 2009) Ephemeral water bodies are often optimal for breeding as they tend to be shallower and warmer which maximises tadpole growth rate (van Dam et al 2002) There is a clear preference for shallow pools with gradual rather than steep slopes and open (un-vegetated) gradually sloping muddy banks Sites with flowing water or with steep slopes andor densely vegetated banks are avoided (Hagman amp Shine 2006)

Fertilisation is external Females lay their eggs within long gelatinous strings (DEWHA 2005a) Environmental factors such as temperature and water composition can affect the gender ratio of tadpoles (Easteal 1993)

7

I n v a s i v e a n i m a l r i s k a s s e s s m e n t Cane toad Bufo marinus

The length of the tadpole stage varies considerably depending on climate competition and the availability of food (Hero amp Stoneham 2009) In the tropics tadpoles mature more quickly than in temperate regions (Australian Museum 2003)

Where favourable conditions exist tadpoles can form schools of tens of thousands However only about 05 of tadpoles survive to maturity

Tadpoles can produce alarm pheromones in response to disturbance or injury Moreover both larval and post-metamorphic toads respond strongly to chemical cues from crushed or injured cohorts consistently fleeing from the stimulus (Hagman amp Shine 2008a) Tadpoles exposed to these pheromones metamorphose more quickly and at a smaller size than unexposed cohorts When they mature they also develop larger parotoid glands The ability to invest varying resources into defensive toxins and to accelerate development is probably a response to predation pressure (Hagman et al 2009)

During the dry season when insect prey is scarce some juvenile toads become cannibals Individuals that are 80ndash110 mm long can rapidly wave the long middle toe on their hind foot to lure smaller toads Up to two-thirds of total prey biomass can consist of metamorph toads caught in this manner and the high densities of metamorphs around water bodies can provide exceptional feeding opportunities (Child et al 2009 Hagman amp Shine 2008b Pizzatto amp Shine 2008) The presence of cannibalistic individuals along the edges of waterways causes metamorphs to disperse although this response can increase risk of desiccation (Child et al 2008b) Since larger toads are nocturnal diurnal activity by metamorphs is a behavioural response to avoid cannibalism (Pizzatto et al 2008)

While in the process of invading new habitat cane toads seem to enjoy a period of unusually high abundance For example densities of up to 2138 toads per hectare have been recorded at an invasion front in the Gulf of Carpentaria Abundance seems to decline over time (Freeland 1986) presumably as food supplies become exhausted

Adult toads tend to move more extensively during the wet season During the dry season they seek shelter sites (such as deep burrows) that provide protection from desiccation (Schwarzkopf amp Alford 2002) Males tend to stay around breeding ponds calling to attract females whereas females tend to wander over larger areas feeding to accumulate energy needed to produce eggs (CaneToadsinOzcom 2009)

DietCane toads are opportunistic omnivorous and fearless predators and will eat almost anything they can catch and swallow Their diet is predominantly comprised of small terrestrial arthropods (such as beetles spiders centipedes millipedes ants winged termites and crickets) but also includes larger items such as marine snails other (smaller) toads frogs small snakes small mammals small birds earthworms planarians rotting fruit carrion household scraps and processed pet food Adults can consume up to 200 food items per night significantly more than native frogs

After hatching tadpoles initially feed on the gelatinous string that held the eggs together Rasping mouth parts then allow tadpoles to feed on aquatic plants and detritus Fine nutrient particles are ingested by filter feeding (Australian Museum 2003 DEWHA 2005a Easteal 1993)

8

I n v a s i v e a n i m a l r i s k a s s e s s m e n t Cane toad Bufo marinus

Predators and diseasesPredators include wolf spiders freshwater crayfish estuarine crocodiles crows white-faced herons kites bush stone-curlews tawny frogmouths water rats giant white-tailed rats and keelback snakes (Australian Museum 2003) Keelbacks (Tropidonophis mairii) are more than 70 times more resistant to cane toad toxin than most other Australian snakes and can regularly consume toads and survive However cane toads have lower nutritional value and take longer to consume than native frogs and can also reduce locomotor ability for up to six hours after ingestion possibly increasing the snakesrsquo vulnerability to predation (Llewelyn et al 2009)

Two species of meat ants (Iridomyrmex purpureus and I reburrus) have been observed eating recently metamorphosed toads (Clerke amp Williamson 1992) Compared to native frogs very young cane toads appear less able to escape meat ants (Ward-Fear et al 2009)

Some predators such as crows have learnt to eat only the tongue of B marinus or to attack the belly and eat only the mildly poisonous internal organs (Australian Museum 2003) They are often seen picking at toads that have been run over by vehicles on roads

B marinus tadpoles are consumed by dragonfly naiads dytiscid beetles water scorpions (Lethocerus sp) notonectids (Anisops sp) leeches tortoises Macrobrachium spp and crayfish The most frequent predators are older B marinus tadpoles (Hero amp Stoneham 2009)

Cane toads carry the lung nematode Rhabdias pseudosphareocephala which is native to South America In metamorphs infection causes reduced rates of survival and growth Toads at the front line of their invasion path across northern Australia are free from these parasites (Dubey amp Shine 2008)

B marinus in Darwin have been found to suffer from spinal arthropathy as well as joint changes such as thinning cartilage It is possible that the excessive physical activity at the invasion front is predisposing them to degenerative joint changes (Shilton et al 2008)

B marinus is believed to carry the chytrid fungus a significant disease of native frogs

9

I n v a s i v e a n i m a l r i s k a s s e s s m e n t Cane toad Bufo marinus

Origin and distributionB marinus is native to regions from around 30deg N in western Mexico and 27deg N in the Lower Riacuteo Grande Valley in extreme southern Texas (United States) south through Mexico and Central America to around 30deg S in Brazil and Argentina including the Archipieacutelago de las Perlas off the Pacific coast of Panama and Trinidad Tobago and little Tobago off the coast of Venezuela

The naturalised (introduced) range of B marinus includes

bull AsiamdashJapan (Ogasawara Islands Ryukyu Islands) Philippines

bull North AmericamdashBermuda Florida (United States)

bull South AmericamdashWest Indies (Antigua Barbados Carriacou) Cayman Islands Grenada Guadeloupe Hispaniola (Haiti Dominican Republic) Jamaica Marie Galante Martinique Montserrat Nevis Puerto Rico St Kitts (St Christopher) St Lucia St Vincent Virgin Islands

bull AustralasiamdashAustralia Papua New Guinea

bull OceaniamdashIndian Ocean (Chagos Archipelago Mascarene Islands) Pacific Ocean (American Samoa Federated States of Micronesia Fiji Hawaiian Islands Kiribati Marianas Islands Republic of the Marshall Islands Republic of Palau Solomon Islands Tuvalu)

(Lever 2003)

Figure 2 Worldwide distribution of Bufo marinusmdashblue areas indicate native distribution and red areas indicate naturalised distribution (image LiquidGhoul from Wikimedia Commons under GNU Free Documentation Licence)

10

I n v a s i v e a n i m a l r i s k a s s e s s m e n t Cane toad Bufo marinus

Status in Australia and QueenslandB marinus was introduced to Australia in 1935 The Australian Bureau of Sugar Experimental Stations imported about 100 toads from Hawaii to the Meringa Experimental Station near Cairns They were released in an attempt to control Frenchrsquos cane beetle and the greyback cane beetle the larvae of which eat the roots of sugarcane and kill or stunt the plants The initial 100 toads bred quickly and more than 3000 were released in the sugarcane plantations of north Queensland in July 1935 There was a brief moratorium on further releases following protest by some naturalists and scientists but releases resumed in 1936 (Australian Museum 2003) Initially cane toads spread south and west They were first recorded in Brisbane in the 1940s and occupied approximately half of Queensland by the late 1990s They were recorded in north-eastern New South Wales in early 1960s and crossed into the Northern Territory during the 1980s (DEWHA 2005a) The first cane toads invaded Kakadu National Park in the summer of 2000ndash2001 (Hero amp Stoneham 2009)

At present B marinus is abundant across vast areas of tropical and subtropical coastal and sub-coastal northern Australia especially Queensland and northern New South Wales Active invasion and population development is currently occurring in coastal Northern Territory and north-west Western Australia The speciesrsquo total range is estimated to cover more than 1 million km2 across tropical and subtropical Australia (Phillips et al 2007) Along the east coast of Australia their range extends from Cape York Peninsular to Port Macquarie in New South Wales with individuals regularly being found further south In Queensland small populations have been recorded as far west as Richmond and Roma

Population expansion is most rapid in regions with hot weather abundant breeding habitat low elevation and high road density In parts of northern Australia invasion rates of 27 km per year have been recorded (Freeland amp Martin 1985) There is evidence that cane toads utilise roads as dispersal corridors into previously unoccupied areas In the Northern Territory radio-tracked toads have been recorded moving up to 18 km per night along roads and cleared fence lines avoiding heavily vegetated habitat and sheltering overnight close to these open corridors returning to the road each evening to recommence dispersal (Brown et al 2006) In less suitable habitat (such as hot dry regions of the interior and in cooler regions in southern Australia) range expansion occurs more slowly

Research has revealed that cane toads at the front of their invasion path have longer legs than animals in older established populations Longer legs probably facilitate more rapid dispersal Populations during the 1940s to 1960s expanded at a rate of about 10 km per annum The current expansion rate (gt 50 km per annum) may be due to rapid adaptive change and continual spatial selection at the expanding front favouring traits that increase dispersal such as longer legs (Phillips et al 2006) In about 50 generations B marinus in Australia have changed from populations in which many individuals move short distances and returned to the same shelter sites to ones with a much higher proportion of toads likely to make long straight moves to new locations every night (Alford et al 2009)

11

I n v a s i v e a n i m a l r i s k a s s e s s m e n t Cane toad Bufo marinus

Cane toads are readily moved over long distances by people A study of toads in Sydney found that the main method of arrival was road transport (eg toads arriving as stowaways in landscaping supplies) To date breeding has been unsuccessful in the Sydney region However a period of prolonged warm wet weather might facilitate successful breeding at some point The ability of B marinus to stowaway on road transport means they are highly likely to disperse across Australia establishing new populations wherever suitable climate and habitat exists (White amp Shine 2009)

Preferred habitatIn general B marinus prefers humid tropical to subtropical lowlands usually close to freshwater breeding habitat (Gautherot 2000) Disturbed or otherwise degraded habitats where the original forest cover has been removed or damaged appear most suitable but open tropical savannah and forests with sparse understoreys are also suitable Optimal habitat includes open cane fields open grazing land lawns and gardens Cane toads tend to be much less common in closed forests or dense native vegetation although they can occupy roads and tracks that run through such areas Open sites such as urban lawns seem to suit the animalrsquos hunting style of sitting waiting for insects and other prey to move past

Cane toads hide during the day under rocks fallen trees loose boards or any shaded cool cover they can find They hunt at night especially on warm wet nights

Habitat utilisation can vary depending on seasonal conditions For example during the dry season in Kakadu National Park Northern Territory cane toads congregate close to creeks billabongs and patches of monsoon rainforest (where there is moisture) During the wet season however they disperse much further into woodlands and open forests of the lowland plains (van Dam et al 2002)

Adults tolerate brackish water and have occasionally been seen swimming in the sea They readily inhabit the margins of estuaries tidal mudflats coastal dunes and coastal mangroves (van Dam et al 2002)

Cane toads can tolerate the loss of up to 50 of their body water and can survive in areas where temperatures range from 5 to 40 degC (Australian Museum 2003) Currently cane toads occupy habitats at elevations ranging from sea level up to 1600 m (Hero amp Stoneham 2009)

12

I n v a s i v e a n i m a l r i s k a s s e s s m e n t Cane toad Bufo marinus

History as a pest elsewhereB marinus is one of the most widely distributed terrestrial vertebrate pests in the Pacific and Caribbean regions (Lever 2003) The species was introduced to many tropical countries and islands in a clumsy attempt to control pests affecting agriculture For example introductions into Jamaica and the Philippines in the late 1800s were aimed at controlling rats Similarly releases into Puerto Rico Fiji New Guinea Hawaii America and Australia in the early 1900s were to control sugarcane pests (Hero amp Stoneham 2009) In some areas B marinus failed to establish or there was an initial population increase followed by a strong decline

Many countries consider B marinus to be either a minor pest or a beneficial form of insect control In some places their impact on native fauna is recognised For example B marinus in the Philippines is believed to compete with native frogs for breeding sites and food (Lever 2003) In Papua New Guinea B marinus may have caused a decline in the abundance of certain native predators such as the Papuan black snake (Pseudechis papuanus) and New Guinea quolls (Dasyurus albopunctatus) that have either mouthed or consumed toads (Lever 2003)

B marinus is a pest of apiarists in Australia and Bermuda since they eat bees as they leave or enter their hives Honey production losses of over $1 million per year have been estimated

In Barbados B marinus is considered a pest of plant nurseries due to its habit of burying itself in moist potting mix thereby crushing delicate seedlings Similarly B marinus causes damage to seed beds in Grenada and tramples commercial lettuce beds on St Lucia in the West Indies (Bomford et al 2005)

Current impact in AustraliaB marinus has invaded large areas of tropical and subtropical Australia across a range of habitats While there is a general perception that B marinus has significant negative impacts on native wildlife (especially predators) there is limited quantitative information (especially on long-term impacts) Most information is anecdotal or inconclusive at a population or species level (DEWHA 2005a)

Native predators that have died after eating or attempting to eat cane toads include goannas freshwater crocodiles tiger snakes red-bellied black snakes death adders dingoes and quolls (Australian Museum 2003) The northern quoll (Dasyurus hallucatus) is currently suffering a serious population decline In fact B marinus is listed as a lsquoKey Threatening Processrsquo for northern quolls under the Australian Governmentrsquos Environment Protection and Biodiversity Conservation Act 1999 In some areas such as Cape York and Kakadu National Park quolls rapidly disappeared following the arrival of B marinus and populations have not recovered (DEWHA 2005b)

Letnic et al (2008) found that cane toads caused a 45ndash77 decline in abundance of freshwater crocodiles (Crocodylus johnstoni) in the Victoria River region of the Northern Territory Subadult crocodiles suffered highest mortality rates The removal of these top-order predators is likely to have serious flow-on effects within riparian and aquatic ecosystems in the Northern Territory

13

I n v a s i v e a n i m a l r i s k a s s e s s m e n t Cane toad Bufo marinus

Another study in the Northern Territory found that cane toads caused marked declines in populations of yellow-spotted monitors (Varanus panoptes) Monitors have been reduced to such low numbers that they are no longer significant predators of pig-nosed turtle eggs (Carettochelys insculpta) Prior to the arrival of B marinus annual losses of pig-nosed turtle eggs were 17ndash23 Following invasion losses of pig-nosed turtle eggs no longer occurred (Doody et al 2006) Increased numbers of pig-nosed turtles will probably have flow-on effects for other species

Research on rainbow bee-eater birds (Merops ornatus) in south-east Queensland found that B marinus predation caused 33 of nests to fail B marinus were observed to occupy the birdsrsquo nest burrows for several days or even weeks either eating the eggs or small chicks or starving larger chicks by preventing adult birds from entering their burrows (Boland 2004)

A study on the effect of B marinus toxin on a variety of frog-eating snake species identified 49 species that are potentially at risk Nine of these species are listed as lsquothreatened speciesrsquo at either federal or state levels Moreover B marinus pose a potential threat to 70 of Australian colubrid snakes 40 of pythons and 41 of elapids (Phillips et al 2003)

Seventy-five species of Australian lizards crocodiles and freshwater turtles are threatened by cane toads Sixteen of these are lsquothreatened speciesrsquo at either federal or state levels (Smith amp Phillips 2006)

One reptile species that appears to have adapted to B marinus is the Australian black snake (Pseudechis porphyriacus) In less than 23 generations the black snake population appears to have developed increased resistance to B marinus toxin and an increased reluctance to consume toads (Phillips amp Shine 2006)

The tadpoles of native frogs can die if they consume the eggs of B marinus B marinus tadpoles have also been recorded to reduce the growth rates of native frog tadpoles under certain conditions Fortunately B marinus utilises a smaller range of water bodies for breeding and as such interaction between B marinus and native frog eggs and tadpoles does not always occur However the full extent of interaction and mortality is unknown (Crossland et al 2008 Williamson 1999)

In the Northern Territory several Aboriginal communities have noticed a decline in lsquobush tuckerrsquo species such as monitor lizards snakes and turtles There has also been a loss of totem species such as freshwater crocodiles which are important for traditional ceremonies (van Dam et al 2002)

When an area is first invaded by B marinus the naturally high abundance of invertebrates appears to support a total biomass of B marinus that is up to four times greater than the local frog population (Greenlees et al 2006) As food items are exhausted B marinus abundance appears to decline presumably until it is more or less in equilibrium with its food supply The initial decline in invertebrate prey items that follows the toad invasion front probably has significant flow-on effects to other insectivorous predators and may interrupt ecological processes at least temporarily The significance of these effects and their timescale is largely unknown Some studies have shown that the impact on certain native species may not be as severe as first thought For example planigales (Planigale maculate) were shown to readily consume metamorph B marinus Most survived the initial encounter and quickly learnt to avoid B marinus for up to 28 days It has been suggested that they have learnt to use chemical cues to discriminate between frogs and B marinus following initial interaction

14

I n v a s i v e a n i m a l r i s k a s s e s s m e n t Cane toad Bufo marinus

Hence there is hope that small dasyurid predators might adapt to B marinus invasion over the long term (Webb et al 2008)

Greenlees et al (2007) found that the presence of B marinus did not influence food intake or dietary composition of the morphologically similar native giant burrowing frog (Cyclorana australis) However high densities of anurans (frogs and toads) suppressed frog activity levels

For further information on impact refer to McRae et al (2005)

Pest potential in QueenslandSince B marinus is currently spreading west across northern Australia across the Top End in the Northern Territory and more recently in north-west Western Australia it is important to try and predict its full potential range

Climate matchA speciesrsquo distribution is determined by a complex range of environmental variables However climate appears to be one of the most influential parameters Using a climate-based modelling tool called CLIMEX (Skarratt et al 1995) this study suggests that large areas of coastal and sub-coastal tropical northern Australia have climate types that are highly suitable for B marinus (Figure 3)

Figure 3 Potential distribution of Bufo marinus in Australia as predicted by climate-matching computer software called CLIMEXmdashareas coloured darkest red indicate areas where climate is considered highly suitable for Bufo marinus grading to lightest red which indicate marginal habitat white indicates unsuitable habitat (model produced by Martin Hannan-Jones Department of Employment Economic Development and Innovation)

15

I n v a s i v e a n i m a l r i s k a s s e s s m e n t Cane toad Bufo marinus

The speciesrsquo predicted range in Queensland is similar to its current observed range suggesting it has filled much of its potential bio-climatic range in the state The potential for further spread into Queenslandrsquos far western arid zone is open to speculationmdashwhile the climate may be generally too hot and dry in this area B marinus might survive within small pockets of moist habitat such as along the banks of watercourses In the Northern Territory large areas of the Top End appear suitable (areas where B marinus is currently invading) as are parts of north-west Western Australia This model suggests that B marinus is unlikely to spread south past Port Macquarie in New South Wales (where it currently exists) and that large areas of southern Australia are climatically unsuitable

The climate-based prediction of potential range presented above can be compared to other published models To date there have been two main approaches used to model and predict the potential range of B marinus in Australiamdashcorrelative and mechanistic The former published by Urban et al (2007) was based on presence and absence data It used a number of climatic variables recorded across the naturalised range of B marinus namely annual temperature annual precipitation minimum moisture index mean annual evaporation elevation topographical heterogeneity road cover and urban land use This model predicted that B marinus could eventually occupy 2 million kmsup2 of Australia including 76 of the coastline

The mechanistic approach published by Kearney et al (2008) does not use speciesrsquo occurrence data Instead it links key eco-physiological traits with spatial data using biophysical models This model predicts that the major constraints to potential range in Australia may be climatically imposed limitations on movement potential in adult B marinus at southern range borders and the availability of water for breeding in natural ponds at the interior limit It predicts B marinus will not survive in large parts of southern Australia but may occupy extensive areas of central Australia

The potential impacts of cane toads are difficult to predict However based on available evidence it seems reasonable to expect further declines in certain native predator populations especially the northern quoll Native predator species that adapt by learning not to eat toads may recover Further research is needed to predict impacts

Threat to human healthAt all developmental stages (including eggs) tadpoles and adults are poisonous though young tadpoles are the least toxic Paratoid glands just behind the head produce and store a mixture of bufotenine and epinephrine which are steroid-like substances toxic to most animals These substances have a digitalis-like action on the heart

Humans poisoned by B marinus experience vomiting increased blood pressure increased pulse rate increased rate and depth of respiration severe headache and paralysis While there have not been any deaths in Australia people have died overseas after eating toads or soup made from toad eggs People have been reported to smoke the dried parotoid glands or lick the back of toads for hallucinogenic effects produced by the toxins This form of substance abuse has occurred in north Queensland and in Fiji

16

I n v a s i v e a n i m a l r i s k a s s e s s m e n t Cane toad Bufo marinus

Domestic pets such as dogs and cats and native wildlife can be poisoned often with fatal consequences Symptoms include rapid heartbeat profuse salivation twitching vomiting shallow breathing and collapse of the hind limbs Death from cardiac arrest may occur within 15 minutes

B marinus responds to a threat by turning side-on so its parotoid glands are directed towards the attacker The toxin usually oozes out of the glands but toads can squirt a fine spray for a short distance if they are handled roughly The toxin is absorbed through mucous membranes such as eyes mouth and nose and in humans may cause intense pain temporary blindness and inflammation (Australian Museum 2003 Hero amp Stoneham 2009 Nellis 1997 van Dam et al 2002)

Numerical risk analysisA numerical risk assessment system developed by Bomford (2008) is widely applied in Australia to assess the level of risk posed by vertebrates This approach enables numerical ranking and prioritisation of large numbers of species Firstly a speciesrsquo potential distribution is predicted using climate-modelling computer programs The remaining steps involve allocation of scores for a number of attributes relevant to a speciesrsquo pest status including biology costs to the economy the environment and society and management efficacy

Using the Bomford system cane toads were assessed as an lsquoextremersquo threat species (refer to Attachment 1)

17

I n v a s i v e a n i m a l r i s k a s s e s s m e n t Cane toad Bufo marinus

ReferencesAlford RA Brown GP Schwarzkopf L Phillips BL amp Shine R (2009) lsquoComparisons through time and space suggest rapid evolution of dispersal behaviour in an invasive speciesrsquo Wildlife Research 36 23ndash28

Australian Museum (2003) Cane Toads Giant Toads or Marine Toads lthttpwwwaustmusgovaufactsheetscanetoadhtmgt

Boland CRJ (2004) lsquoIntroduced cane toads Bufo marinus are active nest predators and competitors of rainbow bee-eaters Merops ornatus observational and experimental evidencersquo Biological Conservation 120 53ndash62

Bomford M (2008) Risk assessment models for the establishment of exotic vertebrates in Australia and New Zealand validating and refining risk assessment models Invasive Animals Cooperative Research Centre Canberra

Bomford M Kraus F Braysher M Walter L amp Brown L (2005) Risk assessment model for the import and keeping of exotic reptiles and amphibians lthttpwwwferalorgauferal_documentsRepAmphRiskpdfgt

Brown GP Phillips BL Webb JK amp Shine R (2006) lsquoToad on the road Use of roads as dispersal corridors by cane toads (Bufo marinus) at an invasion front in tropical Australiarsquo Biological Conservation 133 88ndash94

CaneToadsinOzcom (2009) Cane Toads in Oz lthttpwwwcanetoadsinozcomindexhtmlgt

Chaparro JC Pramuk JB amp Gluesenkamp AG (2007) lsquoA new species of arboreal Rhinella (Anura Bufonidae) from cloud forest of southeastern Perursquo Herpetologica 63(2) 203ndash212

Child T Phillips BLamp Shine R (2009) lsquoDoes desiccation risk drive the distribution of juvenile cane toads (Bufo marinus) in tropical Australiarsquo Journal of Tropical Ecology 25 193ndash200

Clerke RB amp Williamson I (1992) lsquoA note on the predation of Bufo marinus juveniles by the ant Iridomyrmex purpureusrsquo Australian Zoologist 28(1ndash4) 64ndash67

Crossland MR Brown GP Anstis M Shilton CM amp Shine R (2008) lsquoMass mortality of native anuran tadpoles in tropical Australia due to the invasive cane toad (Bufo marinus) Biological Conservation 141 2387ndash2394

Department of Agriculture and Food WA (2008) Agriculture and Related Resources Protection Act 1976 lthttpwwwagricwagovaucontentPWVPdeclared_animalspdfgt

Department of Primary Industries and Water (2008) Requirements for Importing Animals to Tasmania lthttpwwwdpiwtasgovauinternsfWebPagesEGIL-5366L4opengt

Department of Territory and Municipal Services (2005) Pest Plants and Animals (Pest Animals) Declaration 2005 (No 1) lthttpwwwlegislationactgovaudi2005-255currentpdf2005-255pdfgt

DEWHA (2005a) Department of the Environment Water Heritage and the Arts The biological effects including lethal toxic ingestion caused by Cane Toads (Bufo marinus) lthttpwwwenvironmentgovaubiodiversitythreatenedktpcane-toadshtmlgt

18

I n v a s i v e a n i m a l r i s k a s s e s s m e n t Cane toad Bufo marinus

DEWHA (2005b) Department of the Environment Water Heritage and the Arts Threatened Species and threatened ecological communitiesmdashNorthern Quoll (Dasyurus hallucatus) lthttpwwwenvironmentgovaubiodiversitythreatenedspeciesdasyurus-hallucatushtmlgt

Doody JS Green B Sims R Rhind D West P amp Steer D (2006) lsquoIndirect impacts of invasive cane toads (Bufo marinus) on nest predation in pig-nosed turtles (Carettochelys insculpta)rsquo Wildlife Research 33 349ndash354

Dubey S amp Shine R (2008) lsquoOrigin of the parasites of an invading species the Australian cane toad (Bufo marinus) are the lungworms Australian or Americanrsquo Molecular Ecology 17 4418ndash4424

Easteal S (1993) lsquoFamily Bufonidaersquo Chapter 11 in Fauna of Australia Volume 2A Amphibia and Reptilia AGPS Canberralthttpwwwenvironmentgovaubiodiversityabrspublicationsfauna-of-australiapubsvolume2a11-fauna-2a-amphibia-bufonidaepdfgt

Freeland WJ (1986) lsquoPopulations of Cane Toad Bufo marinus in Relation to Time since Colonizationrsquo Australian Wildlife Research 13 321ndash329

Freeland WJ amp Martin KC (1985) The rate of range expansion by Bufo marinus in northern Australia 1980ndash84 Australian Wildlife Research 12 555ndash540

Frost DR Grant T Faivovich J Bain RH Haas A Haddad CFB De Saacute RO Channing A Wilkinson M Donnellan SC Raxworthy CJ Campbell JA Blotto BL Moler P Drewes RC Nussbaum RA Lynch JD Green DM amp Wheeler WC (2006) lsquoThe Amphibian Tree of Lifersquo Bulletin of the American Museum of Natural History 297 1ndash370

Gautherot J (2000) Bufo marinus lthttpwwwjcueduauschooltbiolzoologyherpBufomarinusPDFgt

Greenlees MJ Brown GP Webb JK Phillips BL amp Shine R (2007) lsquoDo invasive cane toads (Chaunus marinus) compete with Australian frogs (Cyclorana australis)rsquo Austral Ecology 32 900ndash907

Greenlees MJ Brown GP Webb JK Phillips BL amp Shine R (2006) lsquoEffects of an invasive anuran [the cane toad (Bufo marinus)] on the invertebrate fauna of a tropical Australian floodplainrsquo Animal Conservation 9(4) 431ndash438

Hagman M Hayes RA Capon RJ amp Shine R (2009) lsquoAlarm cues experienced by cane toad tadpoles affect post-metamorphic morphology and chemical defencesrsquo Functional Ecology 23 126ndash132

Hagman M amp Shine R (2008a) lsquoUnderstanding the toad code Behavioural responses of cane toad (Chaunus marinus) larvae and metamorphs to chemical cuesrsquo Austral Ecology 33 37ndash44

Hagman M amp Shine R (2008b) lsquoDeceptive digits the functional significance of toe waving by cannibalistic cane toads Chaunus marinusrsquo Animal Behaviour 75 123ndash131

Hagman M amp Shine R (2006) lsquoSpawning site selection by feral cane toads (Bufo marinus) at an invasion front in tropical Australiarsquo Austral Ecology 31 551ndash558

19

I n v a s i v e a n i m a l r i s k a s s e s s m e n t Cane toad Bufo marinus

Hero JM amp Stoneham M (2009) Bufo marinus lthttpamphibiaweborgcgi-binamphib_queryquery_src=aw_search_indexamptable=amphibampspecial=one_recordampwhere-genus=Bufoampwhere-species=marinusgt

Kearney M Phillips BL Tracy CR Christian KA Betts G amp Porter WP (2008) lsquoModelling species distributions without using species distributions the cane toad in Australia under current and future climatesrsquo Ecography 31 423ndash434

Lee JC (2001) lsquoEvolution of a Secondary Sexual Dimorphism in the Toad Bufo marinusrsquo Copeia 4 928ndash935

Letnic M Webb JK amp Shine R (2008) lsquoInvasive cane toads (Bufo marinus) cause mortality of freshwater crocodiles (Crocodylus johnstoni) in tropical Australiarsquo Biological Conservation 141 1773ndash1782

Lever C (2003) Naturalized Reptiles and Amphibians of the World Oxford University Press

Llewelyn JS Phillips BL amp Shine R (2009) lsquoSublethal costs associated with the consumption of toxic prey by snakesrsquo Austral Ecology 34 179ndash184

McRae D Kennett R amp Taylor R (2005) The Current Threat Posed by Cane Toads Chapter 2 in A Review of the Impact and Control of Cane Toads in Australia with Recommendations for Future Research and Management Approaches lthttpwwwferalorgauferal_documentsCaneToadReport2pdfgt

Nellis DW (1997) Poisonous Plants and Animals of Florida and the Caribbean Pinapple Press Inc

New South Wales State Government (2006) Non-Indigenous Animals Regulation 2006 lthttpwwwlegislationnswgovauviewtopinforcesubordleg+519+2006+cd+0+Ndq= Regulations20under20Non-Indigenous20Animals20Act20198720No20166gt

Northern Territory Government (2007) Natural Resources Environment The Arts and Sport ndash Exotic Animals lthttpwwwntgovaunretawildlifeanimalsexoticindexhtmlgt

Phillips BL Chipperfield JD amp Kearney MR (2008) lsquoThe toad ahead challenges of modelling the range and spread of an invasive speciesrsquo Wildlife Research 35 222ndash234

Phillips BL Brown GP Greenlees M Webb JK amp Shine R (2007) lsquoRapid expansion of the cane toad (Bufo marinus) invasion front in tropical Australiarsquo Austral Ecology 32 169ndash176

Phillips BL amp Shine R (2006) lsquoAn invasive species induces rapid adaptive change in a native predator cane toads and black snakes in Australiarsquo Proceedings of the Royal Society B 273 1545ndash1550

Phillips BL Brown GP Webb JK amp Shine R (2006) lsquoInvasion and the evolution of speed in toadsrsquo Nature 439 803

Phillips BL Brown GP amp Shine R (2003) lsquoAssessing the Potential Impact of Cane Toads on Australian Snakesrsquo Conservation Biology 17(6) 1738ndash1747

Pizzatto L amp Shine R (2008) lsquoThe behavioural ecology of cannibalism in cane toads (Bufo marinus)rsquo Behavioural Ecology and Sociobiology 63(1) 123ndash133

20

I n v a s i v e a n i m a l r i s k a s s e s s m e n t Cane toad Bufo marinus

Pizzatto L Child T amp Shine R (2008) lsquoWhy be diurnal Shifts in activity time enable young cane toads to evade cannibalistic conspecificsrsquo Behavioural Ecology 19(5) 990ndash997

Queensland Government (2006) Land Protection (Pest and Stock Route Management) Act 2002 lthttpwwwlegislationqldgovauLEGISLTNCURRENTLLandPrPSRMA02pdfgt

Seebacher F amp Alford RA (1999) lsquoMovement and Microhabitat Use of a Terrestrial Amphibian (Bufo marinus) on a Tropical Island Seasonal Variation and Environmental Correlatesrsquo Journal of Herpetology 33(2) 208ndash214

Schwarzkopf L amp Alford RA (2002) lsquoNomadic movement in tropical toadsrsquo OIKOS 96 492ndash506

Shilton CM Brown GP Benedict S amp Shine R (2008) lsquoSpinal Arthropathy Associated with Ochrobactrum anthropi in Free-ranging Cane Toads (Chaunus [Bufo] marinus) in Australiarsquo Veterinary Pathology 45 85ndash94

Skarratt DB Sutherst RW amp Maywald GF (1995) CLIMEX for Windows Version 10 Userrsquos Guide computer software for predicting the effects of climate on plants and animals CSIRO and CRC for Tropical Pest Management Brisbane

Smith JG amp Phillips BL (2006) lsquoToxic tucker the potential impact of Cane Toads on Australian reptilesrsquo Pacific Conservation Biology 12 40ndash49

Soliacutes F Ibaacutenez R Hammerson G Hedges B Diesmos A Matsui M Hero JM Richards S Coloma LA Ron S La Marca E Hardy J Powell R Bolanos F amp Chaves G (2008) IUCN Red List of Threatened SpeciesmdashRhinella marina lthttpwwwiucnredlistorgdetails41065gt

South Australian Government Gazette (2005) Natural Resources Management Act 2004mdashDeclaration of Animals and Plants lthttpwwwdwlbcsagovauassetsfileslbsap_declarationofplantsandanimalspdfgt

State of Victoria Department of Primary Industries (2007) A guide for the control over the possession trade and movement of declared pest animals lthttpwwwdpivicgovauDPInreninfnsf9e58661e880ba9e44a256c640023eb2e4c317cefcd441f60ca2572a4000a241e$FILELC0303_Mar07pdfgt

Urban MC Phillips BL Skelly DK amp Shine R (2008) lsquoA Toad More Travelled The Heterogeneous Invasion Dynamics of Cane Toads in Australiarsquo The American Naturalist 171(3) 134ndash148

Urban MC Phillips BL Skelly DK amp Shine R (2007) lsquoThe cane toadrsquos (Chaunus [Bufo] marinus) increasing ability to invade Australia is revealed by a dynamically updated range modelrsquo Proceedings of the Royal Society B 274 1413ndash1419

van Dam RA Walden DJ amp Begg GW (2002) A preliminary risk assessment of cane toads in Kakadu National Park Scientist Report 164 Supervising Scientist Darwin NT lthttpwwwenvironmentgovaussdpublicationsssrpubsssr164pdfgt

Ward-Fear G Brown GP Greenlees MJ amp Shine R (2009) lsquoMaladaptive traits in invasive species in Australia cane toads are more vulnerable to predatory ants than are native frogsrsquo Functional Ecology 23559ndash568

21

I n v a s i v e a n i m a l r i s k a s s e s s m e n t Cane toad Bufo marinus

Webb JK Brown GP Child T Greenlees MJ Phillips BL amp Shine R (2008) lsquoA native dasyurid predator (common planigale Planigale maculate) rapidly learns to avoid a toxic invaderrsquo Austral Ecology 33 821ndash829

White AW amp Shine R (2009) lsquoThe extra-limital spread of an invasive species via lsquostowawayrsquo dispersal toad to nowherersquo Animal Conservation 12 38ndash45

Wikipedia (2009a) Cane Toad lthttpenwikipediaorgwikiCane_toadgt

Wikipedia (2009b) Bufo lthttpenwikipediaorgwikiBufogt

Williamson I (1999) lsquoCompetition between the larvae of the introduced cane toad Bufo marinus (Anura Bufonidae) and native anurans from the Darling Downs area of southern Queenslandrsquo Australian Journal of Ecology 24 636ndash643

22

I n v a s i v e a n i m a l r i s k a s s e s s m e n t Cane toad Bufo marinus

Attachment 1Table 1 Using the Bomford (2008) system cane toads in Queensland were ranked as an lsquoextremersquo threat species

Species Bufo marinus (cane toad)

Date of assessment 2 April 2009

Literature search type and date See references

Factor Score

A1 Risk to people from individual escapees (0ndash2) 2 Cane toads are capable of causing fatalities or

serious injury to people

A2 Risk to public safety from individual captive animals (0ndash2) 1 Moderate risk that toxins of captive animals pose

a public safety risk

Stage A Public safety risk rank = sum of A1 to A2 (0ndash4) 3 Highly dangerous

B1 Climate match (1ndash6) 5

Very high climate match in Australia (CMS = 2041)mdashfrom climate map produced by DAFWA in 2008 using PC Climate software (Bureau of Rural Sciences 2006)

B2 Exotic population established overseas (0ndash4) 4 Cane toads have established in Australia and

across the Caribbean and the Pacific

B3 Overseas range size (0ndash2) 1 Overseas range size of 162 million square kilometres (Bomford et al 2005)

B4 Taxonomic class (0ndash1) 1 Amphibian

B5 Diet (0ndash1) 1

Generalist diet of small terrestrial arthropods such as crabs spiders centipedes millipedes scorpions beetles honeybees ants winged termites crickets and bugsThey are also known to consume marine snails smaller toads and native frogs small snakes small mammals birds earthworms planarians rotting fruit carrion household scraps processed pet food and human faeces

B6 Habitat (0ndash1) 1 Cane toads thrive in degraded and human-made environments

B7 Migratory (0-1) 1 Non-migratory

B Probability escaped or released individuals will establish a free-living population = sum of B1 to B7 (1ndash16)

14 Extreme establishment risk

C1 Taxonomic group (0ndash4) 0 Other group

C2 Overseas range size including current and past 1000 years natural and introduced range (0ndash2)

1 Approximately 162 million square kilometres (Bomford et al 2005)

C3 Diet and feeding (0ndash3) 0 Not a mammal

C4 Competition with native fauna for tree hollows (0ndash2) 2 Cane toads are known to shelter in tree hollows

23

I n v a s i v e a n i m a l r i s k a s s e s s m e n t Cane toad Bufo marinus

Factor Score

C5 Overseas environmental pest status (0ndash3) 3 Major environmental pest in Australia

C6 Climate match to areas with susceptible native species or communities (0ndash5)

5

The species has more than 20 grid squares within the highest two climate match classes and has more than 100 grid squares within the four highest climate match classes that overlap the distribution of any susceptible native species or communities

C7 Overseas primary production pest status (0ndash3) 2 Cane toads are a pest to apiarists and can cause

significant losses

C8 Climate match to susceptible primary production (0ndash5) 1 Total commodity damage score = 75 (see Table 2)

C9 Spread disease (1ndash2) 1 Amphibian

C10 Harm to property (0ndash3) 0 $0

C11 Harm to people (0ndash5) 4

Injuries or harm severe or fatal but few people at riskmdashpeople have died after consuming cane toads or their eggs and their poison can cause temporary blindness

C Probability an exotic species would become a pest (for birds mammals reptiles and amphibians) = sum of C1 to C11 (1ndash37)

19 Serious pest risk

A Risk to public safety posed by captive or released individuals

A = 0 = not dangerous A = 1 = moderately dangerous A ge 2 = highly dangerous

3 Highly dangerous

B Risk of establishing a wild population

For birds and mammals B lt 6 = low establishment risk B = 7ndash11 = moderate establishment risk B = 12ndash13 = serious establishment risk B gt 14 = extreme establishment risk

14 Extreme establishment risk

For reptiles and amphibians B lt 3 = low establishment risk B = 3ndash4 = moderate establishment risk B = 5ndash6 = high establishment risk B gt 6 = extreme establishment risk

C Risk of becoming a pest following establishment

C lt 9 = low pest risk C = 9ndash14 = moderate pest risk C = 15ndash19 = serious pest risk C gt 19 = extreme pest risk

17 Serious pest risk

Vertebrate Pests Committee threat category Extreme

24

I n v a s i v e a n i m a l r i s k a s s e s s m e n t Cane toad Bufo marinus

Table 2 Calculating total commodity damage score

Industry Commodity value index

Potential commodity impact score (0ndash3)

Climate match to commodity score (0ndash5)

Commodity damage score (columns 2 times 3 times 4)

Cattle (includes dairy and beef) 11 0 Not estimated 0

Timber (includes native and plantation forests) 10 0 Not estimated 0

Cereal grain (includes wheat barley sorghum etc) 8 0 Not estimated 0

Sheep (includes wool and sheep meat) 5 0 Not estimated 0

Fruit (includes wine grapes) 4 0 Not estimated 0

Vegetables 3 0 Not estimated 0

Poultry and eggs 2 0 Not estimated 0

Aquaculture (includes coastal mariculture) 2 0 Not estimated 0

Oilseeds (includes canola sunflower etc) 1 0 Not estimated 0

Grain legumes (includes soybeans) 1 0 Not estimated 0

Sugarcane 1 0 Not estimated 0

Cotton 1 0 Not estimated 0

Other crops and horticulture (includes nuts tobacco and flowers)

1 0Not estimated

0

Pigs 1 0 Not estimated 0

Other livestock (includes goats deer camels rabbits)

05 0 Not estimated 0

Bees (includes honey beeswax and pollination) 05 3 5 75

Total commodity damage score 75

The commodity value index is an index of the value of the annual production value of a commodity For a full explanation refer to Bomford (2008)